Design of optimized single-switch capacitor cell balancing for EV battery management

Document Type

Article

Publication Title

Results in Engineering

Abstract

Electric vehicles are at the forefront of the transition towards more sustainable transportation, and battery management systems are tasked with ensuring optimal operation and balancing of the individual cells within a battery pack for increased performance, longevity, and safety of EV batteries. The research explores the implementation of shuttling single-switched capacitor-based active cell balancing in BMS for EVs, aiming to address critical challenges such as balancing speed, energy loss, and system-level complexity. Theoretically, the algorithm for two-cell balance may be extended to any cells in series. However, there are possible modifications to them that may lead to algorithms with improved results. Two algorithms are explored for a four-series connected Li-ion cell battery system. For various scenarios, active cell balancing is performed to determine the time for balance. A thermal-based realistic battery model with non-ideal switching components and a shuttling capacitor with internal resistance is considered to maintain consistency for the comparative performance study in the proposed algorithms. The thermal analysis provides information on the effect of temperature raise during cell balancing of each cell, thereby, its performance during cell balancing. The novelty of this study is the development of a selective combinational control algorithm based on the shuttling switched capacitor method, which dynamically switches between two balancing strategies depending on the number of high-SoC cells relative to the average, enabling efficient any-cell-to-any-cell active balancing across more than two series-connected cells. The MATLAB-simulation results confirm a general methodology that can be extended to any number of cells, which is an effective combinational solution to provide optimum cell balancing time with shuttling capacitor-based active cell balancing.

DOI

10.1016/j.rineng.2025.105878

Publication Date

9-1-2025

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